Air-conditioning apparatus

ABSTRACT

A cycle-side system ( 20 ) is formed by duct connecting a compressor ( 21 ), a heat exchanger ( 30 ), a demoisturizer ( 22 ), and an expansion device ( 23 ) in that order. The compressor ( 21 ) draws in room air and supply air for ventilation and compresses the same. The compressed air exchanges heat with exhaust air for ventilation in the heat exchanger ( 30 ), thereby being cooled. Water vapor in the cooled, compressed air is removed in the demoisturizer ( 22 ). The demoisturizer ( 22 ) is provided with a separation membrane and separates water vapor in the compressed air without the occurrence of condensation. Thereafter, the compressed air is expanded in the expansion device ( 23 ) to change into low-temperature air. The low-temperature air is supplied into a room. On the other hand, the heat exchanger ( 30 ) is fed exhaust air cooled in a humidifying cooler ( 41 ). Further, in the heat exchanger ( 30 ), a latent heat of vaporization of moisture supplied by a humidifying part ( 42 ) is also utilized for cooling of the compressed air.

TECHNICAL FIELD

The present invention relates to an air cycle air-conditioning apparatusemploying air as a refrigerant and, more particularly, to an efficiencyimproving scheme.

BACKGROUND ART

Cooling apparatus of the air cycle type in which air serves as arefrigerant have been conventionally known in the art. For example,there is disclosed in Japanese Unexamined Patent Gazette No. S62-102061one type of air cycle cooling apparatus. This type of cooling apparatusincludes a compressor, a heat exchanger, and an expansion device. Thatis, air is drawn into the compressor where the air is compressed. Thecompressed air is cooled in the heat exchanger and thereafter expandedin the expansion device, for obtaining low-temperature air of lowtemperature. In the cooling apparatus of the aforesaid Patent Gazette,the cooling air thus obtained is used for achieving cooling of theinside of a room. Further, in the cooling apparatus, the low-temperatureair expanded in the expansion device is sprayed with water so that the-temperature of the low-temperature air is lowered to a further extentby evaporation of the water for enhancing cooling capacity.

PROBLEMS TO BE SOLVED

However, in the aforesaid conventional cooling apparatus, cooling of aircompressed in the compressor is carried out by heat exchange withoutside air. If outside air temperature rises to as high as 35 degreescentigrade in summer, it is impossible for the cooling apparatus tolower the temperature of the compressed air beyond about 40 degreescentigrade. Accordingly, in order to ensure cooling capacity even whenoutside air temperature is high, the compression ratio of the compressormust be increased. As a result, compressor driving power should beincreased, giving rise to the problem of poor cooling efficiency, i.e.,low COP (coefficient of performance).

Bearing in mind the above drawbacks with the prior art, the presentinvention was made. Accordingly, an object of the present invention isto provide an improved COP while at the same time maintaining thecooling capacity of an air cycle air-conditioning apparatus.

DISCLOSURE OF THE INVENTION

In the present invention, the temperature of cooled, compressed air islowered and compressor driving power can be reduced while maintainingcooling capacity.

More specifically, the present invention discloses a first solutionmeans which is directed to an air-conditioning apparatus for coolingroom air by an air cycle employing air as a refrigerant, therebyperforming air-cooling. The air-conditioning apparatus of the firstsolution means comprises a compressor (21) which draws in at least airin a room for compressing the drawn room air, a cooling means (30) whichsubjects the compressed air compressed in the compressor (21) to heatexchange with exhaust air expelled from the room for cooling thecompressed air, and an expansion device (23) which provides-expansion ofthe compressed air cooled by the cooling means (30), whereinlow-temperature air, cooled by the expansion in the expansion device(23), is delivered to the room.

Further, the present invention discloses a second solution meansaccording to the first solution means in which a moisturizing means (41)is disposed which supplies moisture to the exhaust air that is deliveredto the cooling means (30) for pre-cooling the exhaust air.

Further, the present invention discloses a third solution meansaccording to the first solution means in which a moisturizing means (42)is disposed which supplies moisture to the exhaust air so that coolingof the compressed air is performed making utilization of a latent heatof vaporization of water in the cooling means (30).

Further, the present invention discloses a fourth solution meansaccording to the second or third solution means in which, when theexhaust air is expelled from the cooling means (30), each moisturizingmeans (41, 42) supplies a specified amount of moisture to the exhaustair so that the exhaust air has a relative humidity in a range from notless than 80% to less than 100%.

Further, the present invention discloses a fifth solution meansaccording to the second or third solution means in which eachmoisturizing means (41, 42) supplies moisture to the exhaust air througha moisture permeable membrane transmittable to moisture.

Further, the present invention discloses a sixth solution meansaccording to the first solution means in which a demoisturizing means(22) is disposed which has a separation membrane and the separationmembrane is formed such that water vapor in the air is allowed to passtherethrough from a high partial pressure of water-vapor side to a lowpartial pressure of water-vapor side thereof, for separation of watervapor contained in the compressed air without causing the water vapor toundergo condensation.

Further, the present invention discloses a seventh solution meansaccording to the sixth solution means in which a depressurizing means(36) is disposed which provides depressurization of one of the sides ofthe separation membrane in the demoisturizing means (22) so as to ensurea difference in partial pressure of water-vapor between both theseparation membrane sides.

Further, the present invention discloses an eighth solution meansaccording to any one of the second to fifth solution means in which ademoisturizing means (22) is disposed which has a separation membraneand the separation membrane is formed such that water vapor in the airis allowed to pass therethrough from a high partial pressure ofwater-vapor side to a low partial pressure of water-vapor side thereof,for separation of water vapor contained in the compressed air withoutcausing the water vapor to undergo condensation.

Further, the present invention discloses a ninth solution meansaccording to the eighth solution means in which a depressurizing means(36) is disposed which provides depressurization of one of the sides ofthe separation membrane in the demoisturizing means (22) so as to ensurea difference in partial pressure of water-vapor between both theseparation membrane sides.

Further, the present invention discloses a tenth solution meansaccording to the sixth or eighth solution means in which thedemoisturizing means (22) is formed so that one of surfaces of theseparation membrane is brought into contact with the compressed airwhereas the other of the surfaces is brought into contact with theexhaust air, whereby water vapor contained in the compressed air willtravel to the exhaust air.

Further, the present invention discloses an eleventh solution meansaccording to any one of the sixth to ninth solution means in which apart or all of moisture separated from the compressed air by thedemoisturizing means (22) is supplied, together with low-temperature airfrom the expansion device (23), into the room.

Further, the present invention discloses a twelfth solution meansaccording to the ninth solution means in which a part or all of moistureseparated from the compressed air by the demoisturizing means (22) issupplied to the exhaust air by the moisturizing means (41, 42).

Further, the present invention discloses a thirteenth solution meansaccording to any one of the sixth to twelfth solution means in which theseparation membrane is composed of a polymeric membrane and formed so asto allow water vapor to pass therethrough by water-molecule diffusion inthe membrane.

Further, the present invention discloses a fourteenth solution meansaccording to any one of the sixth to twelfth solution means in which theseparation membrane has a large number of pores having a size equal to amolecule free path and is formed so as to allow water vapor to passtherethrough by water-molecule capillary condensation and diffusion.

Further, the present invention discloses a fifteenth solution meansaccording to any one of the first to fourteenth solution means in whichthe compressor (21) is so formed as to draw in room air and supply airthat is supplied from the outside to the inside of the room.

Finally, the present invention discloses a sixteenth solution meansaccording to any one of the first to fifteenth solution means in whichlow-temperature air from the expansion device (23) is mixed with roomair and thereafter the mixture is-supplied into the room.

ACTION

In the first solution means, the compressor (21) compresses at leastroom air which then becomes high-pressure, compressed air. Thecompressed air is cooled in the cooling means (30) and thereafterexpanded in the expansion device (23) to become low-temperature air. Thelow-temperature is supplied into the room for cooling thereof. Here, thetemperature of exhaust air expelled from inside the room for the purposeof ventilation et cetera is approximately the same as room temperature,therefore being lower than outside air temperature. In the presentsolution means, in the cooling means (30) compressed air is cooled withexhaust air the temperature of which is lower than that of outside air.

Further, in the second solution means, the moisturizing means (41)supplies moisture to -exhaust air, so that the temperature of theexhaust air is made lower than that of room air by evaporation of themoisture supplied. And then, in the cooling means (30), the exhaust air,the temperature of which is lower than room temperature, is subjected toheat exchange with compressed air.

Further, in the third solution means, the moisturizing means (42)supplies moisture to exhaust air and the cooling means (30) utilizes asensible heat of the exhaust air and a latent heat of vaporization ofthe moisture for compressed air cooling. That is, in the cooling means(30), the compressed air is cooled while on the other hand the exhaustair is heated, and the moisture supplied to the exhaust air isevaporated. At that time, the temperature rising of the exhaust air issuppressed by such moisture evaporation, thereby maintaining adifference in temperature between the exhaust air and the compressedair.

Further, in the fourth solution means, the moisturizing means (41, 42)supply a possible maximum amount of moisture to exhaust air in such arange that no condensation occurs in the exhaust air when it is expelledfrom the cooling means (30). Accordingly, compressed air cooling iscarried out by making utilization of a latent heat of vaporization ofthe moisture to the full extent.

Further, in the fifth solution means, moisture is gradually supplied,through a specified moisture permeable membrane, to exhaust air by themoisturizing means (41, 42).

Further, in the sixth or eighth solution means, the demoisturizing means(22) removes moisture from the air compressed in the compressor (21). Atthat time, since the demoisturizing means (22) has a specifiedseparation membrane, moisture in the compressed air is removedtherefrom, still remaining in the form of water vapor.

Further, in the seventh or ninth solution means, depressurizationprovided by the depressurizing means (36) ensures creation of adifference in partial pressure of water-vapor between both the sides ofthe separation membrane. That is, one surface of the separation membranecomes into contact with compressed air and the other surface issubjected to depressurization by the depressurizing means (36).Accordingly, the partial pressure of water-vapor of the other surfaceside of the separation membrane is held lower than that of thecompressed air.

Further, in the tenth solution means, one surface of the separationmembrane is brought into contact with compressed air and the othersurface thereof is brought into contact with exhaust air. Accordingly,in a running condition in which the exhaust air is lower in partialpressure of water-vapor than the compressed air, moisture in thecompressed air travels to the exhaust air without any external action.

Further, in the eleventh solution means, moisture separated fromcompressed air is used for room humidification. Here, if moisture isseparated from compressed air, this may result in gradual drop of theroom humidity. On the other hand, in the present solution means, a partor all of moisture separated is brought back into the room, therebyproviding protection against excessive drop in the room humidity.

Further, in the twelfth solution means, moisture separated fromcompressed air is supplied to exhaust air by the moisturizing means (41,42) and a latent heat of vaporization of that moisture is utilized forcooling of compressed air in the cooling means (30).

Further, in the thirteenth or fourteenth solution means, the separationmembrane is so formed by a given process so that it allows water vaporto pass therethrough.

Further, in the fifteenth solution means, supply air that is suppliedfrom the outside to the inside of a room is supplied, together with roomair, to the compressor (21). The supply air is for ventilation and thetemperature of the supply air is substantially the same as outside airtemperature. Together with the room air, the supply air flows throughthe compressor (21), through the cooling means (30), and through theexpansion device (23) in that order. After it is cooled, the supply airis supplied into the room.

Further, in the sixteenth solution means, even when the temperature ofthe low-temperature air becomes considerably low depending upon therunning condition, the low-temperature air is mixed with mixing air,whereby the temperature of the low-temperature air when it is suppliedinto the room will not become that low.

EFFECTS

In accordance with the above-described solution means, compressed aircooling is carried out using exhaust air. This makes it possible to coolthe compressed air to lower temperatures when compared to cooling withoutside air. Because of this, it is possible to achieve reduction in theinput to the compressor (21) while maintaining cooling capacity, therebyproviding an improved COP.

In respect to the above point, a description will be given withreference to a graph of FIG. 3. First, when compressed air is cooledwith outside air, it is required that compression ratio be increased sothat the compressed air becomes able to give off heat to the outsideair. More specifically, it is required that the air be compressed fromPoint A to Point B′, and a compression work of the compressor (21) isWcom′. The compressed air is cooled from Point B′ to Point C′ andthereafter subjected to expansion from Point C′ to Point D in theexpansion device (23), thus becoming low-temperature air. At that time,a recovery work of the expansion device (23) is Wexp′. Therefore, theinput required is (Wcom′−Wexp′).

On the other hand, when compressed air is cooled with exhaust air thetemperature of which is lower than that of outside air, this enables thecompressed air to give off heat to the exhaust air even at lowcompression ratio. More specifically, compression of the air from PointA to Point B will suffice, and a compression work of the compressor (21)is Wcom. The compressed air is cooled down from Point B to Point C andthereafter subjected to expansion from Point C to Point D in theexpansion device (23), thus becoming low-temperature air. At that time,a recovery work of the expansion device (23) is Wexp. Therefore, theinput required is (Wcom−Wexp).

Accordingly, if compressed air is cooled with exhaust air, this reducesthe required input from (Wcom′−Wexp′) to (Wcom−wexp). In both of thecases, the cooling capacity is Qref. Here, COP is found by dividingcooling capacity by input. Accordingly, the arrangement that compressedair is cooled with exhaust air makes it possible to achieve reduction inthe input while maintaining cooling capacity, thereby achieving animproved COP.

Further, in accordance with the second solution means, it is possible toperform cooling of compressed air with exhaust air whose temperature hasbeen further lowered in comparison with room temperature. Because ofthis, it is possible to cool the compressed air to further lowertemperatures, thereby achieving a further improved COP.

Further, in accordance with the third solution means, it is possible tosuppress the temperature rising of exhaust air in the cooling means (30)by evaporation of the moisture supplied. This makes it possible tomaintain a temperature difference between the exhaust air and thecompressed air, therefore promoting the transfer of heat from thecompressed air to the exhaust air. As a result, it is possible to coolthe compressed air to a further lower temperature, thereby achieving afurther improved COP.

Further, in accordance with the fourth solution means, moistureevaporation latent heat is utilized to the full in such a range that nocondensation occurs in the exhaust air, for compressed air cooling.Because of this, it is possible to cool compressed air by makingutilization of moisture evaporation latent heat without the necessity toprocess drain water.

Further, in accordance with the fifth solution means, moisture issupplied little by little to the exhaust air, thereby ensuring that themoisture supplied is evaporated positively in the exhaust air. As aresult, the moisture supplied into the exhaust air will not remain inthe phase of liquid. Accordingly, moisture evaporative latent heat isutilized to the full for compressed air cooling without taking intoconsideration the processing of drain at all.

Further, in accordance with the sixth or eighth solution means, it ispossible to deliver, after separation of moisture from compressed air,the compressed air to the expansion device (23). This makes it possibleto provide expansion of the compressed air that does not contain thereinmuch moisture, thereby preventing the occurrence of condensation in thepost-expansion low-temperature air. As a result, it becomes possible toperform room cooling while preventing emission of liquid dropletstogether with low-temperature air into the room.

Further, in accordance with the present solution means, it is possibleto separate moisture from the compressed air in the form of water vaporwithout the occurrence of condensation. As a result, it is possible toincrease cooling capacity, thereby achieving an improved COP.

In respect to the above point, a description will be given withreference to a graph of FIG. 4. First, when moisture is not removed fromthe compressed air, a refrigeration cycle in such a case is indicated byPoint A, Point B, Point C′, and Point D′, and the cooling capacity isQref′. On the other hand, when moisture is separated from the compressedair in the form of water vapor, it is possible to lower the enthalpy ofthe post-cooling compressed air by enthalpy held by the separated watervapor. More specifically, the compressed air can be placed in the stateof Point C and a refrigeration cycle in this case is indicated by PointA, Point B, Point C, and Point D, and the cooling capacity is Qref. Boththe cases are substantially identical not only in the compression workof the compressor (21) but also in the recovery work of the expansiondevice (23), so that the input varies little. Accordingly, it ispossible to increase the cooling capacity from Qref′ to Qref withoutincreasing the input, thereby achieving an improved COP.

Further, in accordance with the seventh or ninth solution means, it ispossible to ensure, in any operating condition, a difference in partialpressure of water-vapor between both the sides of the separationmembrane by the depressurization means (36). Accordingly, it is possibleto separate water vapor from the compressed air at all times by theseparation membrane, thereby making it possible to provide stablerunning operations while achieving an improved COP. Further, even duringstart-up it is possible to ensure a difference in partial pressure ofwater-vapor between both the sides of the separation membrane.Accordingly, in accordance with the present solution means, it ispossible to shorten the time taken to achieve sufficient coolingcapacity from the start time.

Further, in accordance with the tenth solution means, it is possible toexpel water vapor separated from compressed air to the outside of theroom, together with exhaust air. This eliminates the need for astructure for processing the water vapor separated, therefore achievingstructure simplification.

Further, in accordance with the eleventh solution means, it is possibleto provide protection against excessive drop in room humidity, therebymaking it possible to maintain not only room temperature but also roomhumidity in specified ranges to improve the comfortability of the personpresent in the room.

Further, in accordance with the twelfth solution means, it is possibleto use moisture separated from compressed air for cooling of thecompressed air in the cooling means (30). As a result, it becomespossible to reduce the amount of water required for running operations.

Further, in accordance with the thirteenth or fourteenth solution means,it is possible to ensure that a separation membrane having a specifiedfunction is formed positively.

Further, in accordance with the fifteen solution means, it is possibleto perform operations in which both room air and supply air are used asa refrigerant.

Further, in accordance with the sixteenth solution means, it is possibleto prevent the temperature of air that is emitted into the room frombecoming too low, thereby maintaining the comfortability of the personpresent in the room.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic arrangement diagram showing an arrangement of anair-conditioning apparatus in accordance with an embodiment of thepresent invention.

FIG. 2 is an air state-diagram showing the operation of theair-conditioning apparatus of the embodiment.

FIG. 3 is a characteristic diagram showing a relationship between thepressure and the enthalpy in an air cycle for providing a description ofthe fact that COP is improved by lowering the temperature of compressedair.

FIG. 4 is a characteristic diagram showing a relationship between thepressure and the enthalpy in an air cycle for providing a description ofthe fact that the cooling capacity is improved by separation of watervapor from compressed air.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described indetail by making reference to the accompanying drawings.

As shown in FIG. 1, an air-conditioning apparatus (10) of the presentembodiment is made up of a cycle-side system (20) and an exhaustheat-side system (40).

The cycle-side system (20) is formed by establishing sequential ductconnection of a compressor (21), a heat exchanger (30), a demoisturizer(22), and an expansion device (23), for performing refrigerationoperations by an air cycle. In addition, the cycle-side system (20)further includes a suction duct (24) connected to the inlet side of thecompressor (21) and an emission duct (25) connected to the outlet sideof the expansion device (23). The suction duct (24) is constructed suchthat it is divided, at its leader end side, into two branches, wherebyroom air and supply air for ventilation supplied from the outside of aroom are delivered to the compressor (21). Further, the emission duct(25) is so formed as to guide low-temperature air from the expansiondevice (23) into the room.

The exhaust heat-side system (40) is formed by establishing ductconnection of a humidifying cooler (41) and the heat exchanger (30) andincludes an inlet duct (43) connected to the humidifying cooler (41) andan outlet duct (44) connected to the heat exchanger (30). The inlet duct(43) opens, at its one end, to the room and is connected, on the way tothe humidifying cooler (41), to a branch duct (45) which is connected,at its one end, to the emission duct (25). The inlet duct (43) isconstructed so that, of the room air flowing therethrough, a partthereof is guided to the humidifying cooler (41) as exhaust air that isexpelled out of the room for ventilation and the remaining air isdelivered to the emission duct (25). Moreover, the outlet duct (44)opens, at its one end, to the outside of the room, whereby exhaust airfrom the heat exchanger (30) is expelled to the outside of the room.

Connected to the compressor (21) is a motor (35). Further, thecompressor (21) is connected to the expansion device (23). Thecompressor (21) is so configured as to be driven by driving force by themotor (35) and by expansion operation when air is expanded in theexpansion device (23).

Zone formed in the heat exchanger (30) are a compressed air passageway(31) through which compressed air flows and an exhaust air passageway(32) through which exhaust air flows. The compressed air passageway (31)is duct connected, at its one end, to the compressor (21), whereas theother end thereof is connected to the demoisturizer (22). On the otherhand, the exhaust air passageway (32) is duct connected, at its one end,to the humidifying cooler (41), whereas the other end thereof isconnected to the outlet duct (44). The heat exchanger (30) is soconfigured as to perform heat exchange between compressed air of thecompressed air passageway (31) and exhaust air of the exhaust airpassageway (32). That is, the heat exchanger (30) constitutes a coolingmeans for cooling the compressed air by heat exchange with the exhaustair.

Further, mounted in the heat exchanger (30) is a humidifying part (42).In the humidifying part (42), the exhaust air passageway (32) is formedof a moisture permeable membrane and a water-side space is definedopposite across the moisture permeable membrane. Connected to thewater-side space is a water supplying pipe (50) and tap water or thelike is supplied, through the water supplying pipe (50), to thewater-side space. In addition, the moisture permeable membrane is formedso that it allows moisture to pass therethrough, wherein moisture in thewater-side space penetrates through the moisture permeable membrane toexhaust air in the exhaust air passageway (32).

The moisture supplied by the humidifying part (42) evaporates in theexhaust air, thereby suppressing the temperature rising of the exhaustair that is subjected to heat exchange with the compressed air. Thisensures a difference in temperature between the exhaust air and thecompressed air. That is, the humidifying part (42) constitutes amoisturizing means capable of a supply of moisture to the exhaust airfor cooling the compressed air by making utilization of a latent heat ofvaporization.

Furthermore, the humidifying part (42) supplies a specified amount ofmoisture to the exhaust air so that the exhaust air at the exit of theexhaust air passageway (32) of the heat exchanger (30) has a humidity ina range from not less than 80% to less than 100%. As a result of sucharrangement, moisture is supplied to exhaust air in such a range that nocondensation occurs in the exhaust air when discharged to the outside ofthe room.

The demoisturizer (22) has a separation membrane. Separated by theseparation membrane are a high-pressure space and a low-pressure space.The high-pressure space is duct connected, at its inlet side, to thecompressed air passageway (31) of the heat exchanger (30) whereas theoutlet side thereof is duct connected to the expansion device (23).Accordingly, compressed air cooled in the heat exchanger (30) flows intothe high-pressure space. In the demoisturizer (22), water vapor in thecompressed air penetrates through the separation membrane, as a resultof which the water vapor travels from the high-pressure space side tothe low-pressure space side. That is, the demoisturizer (22) constitutesa demoisturizing means capable of removal of moisture from thecompressed air.

The separation membrane is implemented by a polymeric membrane such asfluororesin. The separation membrane is so constructed as to allow watervapor to pass therethrough by water molecule diffusion through themembrane inside. Further, the separation membrane may be formed of aporous membrane for gas separation formed of xerogel et cetera. In thiscase, the moisture in the compressed air penetrates through theseparation membrane by capillary condensation and diffusion of watermolecule.

The humidifying cooler (41) has a moisture permeable membrane. Separatedby the moisture permeable membrane are an air-side space and awater-side space. The air-side space is duct connected, at its inletside, to the inlet duct (43) whereas the outlet side thereof is ductconnected to the exhaust air passageway (32) of the heat exchanger (30).Accordingly, exhaust air flows into the air-side space. Moreover, thewater supplying pipe (50) is connected to the water-side space and tapwater et cetera is supplied, through the water supplying pipe (50), tothe water-side space. On the other hand, the moisture permeable membraneis formed so that it allows moisture to pass therethrough. As a result,moisture in the water-side space penetrates through the moisturepermeable membrane, thus being supplied to the exhaust air in theair-side space. The humidifying cooler (41) is so configured as to lowerthe temperature of exhaust air by evaporation of the moisture suppliedto the exhaust air. That is, the humidifying cooler (41) constitutes amoisturizing means for pre-cooling exhaust air and delivering the sameto the heat exchanger (30).

Connected to the low-pressure space of the demoisturizer (22) is avacuum pump (36). The vacuum pump (36) is disposed for providingdepressurization of the low-pressure space, which constitutes adepressurizing means for ensuring a difference in partial pressure ofwater-vapor between the low-pressure space and the high-pressure space.

Further, connected to the outlet side of the vacuum pump (36) is a firstwater line (51) and a second water line (52). The first water line (51)is connected to the water-side space of the humidifying cooler (41) andto the water-side space of the humidifying part (42) of the heatexchanger (30), for supplying moisture separated from compressed air inthe demoisturizer (22) to both the water-side spaces. On the other hand,the second water line (52) is connected to the branch duct (45), forsupplying, together with room air, moisture separated from compressedair in the demoisturizer (22) into low-temperature air within theemission duct (25).

RUNNING OPERATION

Next, running operation of the air-conditioning apparatus (10) will beexplained with reference to FIG. 2. When in the cycle-side system (20)the compressor (21) is driven by the motor (35), room air and supply airare fed to the compressor (21) through the suction duct (24). Morespecifically, supply air (flow rate: MO) and room air (flow rate: M) aremixed with each other and the mixture is supplied to the compressor(21). In the compressor (21), the air thus supplied is subjected tocompression in a range from Point 1 to Point 2, thereby generatingcompressed air of a flow rate of MO+M. The compressed air is deliveredto the compressed air passageway (31) of the heat exchanger (30).

In the heat exchanger (30), while the compressed air is flowing throughthe compressed air passageway (31) it exchanges heat with exhaust air ofthe exhaust air passageway (32). Because of this, the compressed air iscooled in a range from Point 2 to Point 3. The compressed air thuscooled is directed to the high-pressure space of the demoisturizer (22).

In the demoisturizer (22), moisture: dm is removed from the compressedair in a range from Point 3 to Point 3′ and the enthalpy of thecompressed air falls. More specifically, in the demoisturizer (22), thelow-pressure space is depressurized by the vacuum pump (36), so that thepartial pressure of water-vapor of the low-pressure space is maintainedlower than that of the high-pressure space at all times. The differencein partial pressure of water-vapor between both the spaces allows watervapor in the compressed air to penetrate through the separation membranefor removal of the moisture in the compressed air. At that time, thewater vapor in the compressed air is separated from the compressed airin the form of water vapor without undergoing condensation. Accordingly,there is a corresponding drop in enthalpy of the compressed air to theenthalpy of the separated water vapor.

Thereafter, the compressed air is delivered to the expansion device(23). In the expansion device (23), the compressed air is expanded in arange from Point 3′ to Point 4, thereby becoming low-temperature air.Then, the low-temperature air is supplied, through the emission duct(25), into the room, whereby the room is cooled. At that time, room airis delivered, through the branch duct (45), into the emission duct (25).Accordingly, the low-temperature air, mixed with a specified amount ofroom air, is supplied into the room.

On the other hand, in the exhaust heat-side system (40), exhaust air(flow rate: MO) is delivered, through the inlet duct (43), to theair-side space of the humidifying cooler (41). That is, exhaust airwhose flow rate is the same as that of the supply air is delivered tothe humidifying cooler (41).

In the humidifying cooler (41), moisture (flow rate: m1) is supplied tothe exhaust air at Point 5 and the moisture supplied is evaporated inthe exhaust air. Because of this, the temperature of the exhaust airbecomes lower than room temperature. Then, the temperature-loweredexhaust air is delivered to the exhaust air passageway (32) of the heatexchanger (30).

In the exhaust air passageway (32) of the heat exchanger (30), theexhaust air is subjected to heat exchange with the compressed air of thecompressed air passageway (31) in a range from Point 6 to Point 7. Thatis, in the heat exchanger (30), the compressed air is cooled by thelow-temperature exhaust air from the humidifying cooler (41).

Further, in the heat exchanger (30), moisture (flow rate: m2) issupplied to exhaust air in the exhaust air passageway (32) in thehumidifying part (42). The moisture thus supplied evaporates in theexhaust air in the exhaust air passageway (32), thereby suppressing thetemperature rising of the exhaust air. This accordingly maintains adifference in temperature between the compressed air and the exhaust airin the heat exchanger (30), thereby ensuring that the compressed air iscooled positively.

Here, in the present embodiment, a mixture of room air and supply airfor ventilation flows through the cycle-side system (20) and, on theother hand, only exhaust air for ventilation flows through the exhaustheat-side system (40). Accordingly, in the heat exchanger (30), heatexchange between compressed air (flow rate: MO+M) and exhaust air (flowrate: MO) is carried out. That is, cooling of compressed air isperformed with exhaust air having a flow rate less than that of thecompressed air, which may result in insufficient cooling of thecompressed air.

However, in the present embodiment, there is provided a supply ofmoisture to the exhaust air in the humidifying cooler (41) as well as inthe humidifying part (42). As a result of such arrangement, the -thermalcapacity of the exhaust air within the exhaust air passage way (32)increases by the enthalpy of the water vapor supplied (flow rate:m1+m2). Accordingly, in the present embodiment, it is possible tosufficiently cool the compressed air, only by a flow of exhaust air forventilation through the exhaust air-side system (40).

Further, the humidifying part (42) supplies a specified amount ofmoisture to exhaust air so that the exhaust air has, at the exit of theexhaust air passageway (32), a humidity in a range from not less than80% to less than 100%. That is, a supply of moisture to the exhaust airis provided in such a range that no condensation occurs in the exhaustair when discharged to the outside of the room. Accordingly, a latentheat of vaporization of water is utilized to the full for compressed aircooling while making the processing of drain unnecessitated.

Thereafter, the exhaust air, which has exchanged heat with thecompressed air in the heat exchanger (30), is expelled, by way of theoutlet duct (44), to the outside of the room. That is, in the presentembodiment, compressed air cooling is carried out by making utilizationof exhaust air that is expelled for effecting ventilation from theinside to the outside of the room.

Further, of the moisture separated from the compressed air in thedemoisturizer (22), a part thereof flows into the first water line (51)whereas the remaining part flows into the second water line (52). Themoisture now flowing in the first water line (51) is further dividedinto two streams, i.e., one that is guided to the water-side space ofthe humidifying cooler (41) and the other that is guided to thewater-side space of the humidifying part (42) of the heat exchanger(30). Then, the moisture directed to the humidifying cooler (41) issupplied, through the moisture permeable membrane, to exhaust air andutilized there for cooling of the exhaust air. On the other hand, themoisture directed to the humidifying part (42) is supplied, through themoisture permeable membrane, to exhaust air and utilized there forsuppressing the temperature rising of the exhaust air in the heatexchanger (30). Moreover, the moisture now flowing in the second waterline (52) is directed into the branch duct (45) and supplied, togetherwith room air and low-temperature air, into the room for humidificationof the room.

EFFECTS OF THE EMBODIMENTS

In the present embodiment, exhaust air, the temperature of which islower than outside air temperature, is further cooled in the humidifyingcooler (41) and thereafter subjected to heat exchange with thecompressed air in the heat exchanger (30). As a result of sucharrangement, it becomes possible to cool the compressed air tolower-temperatures than performing cooling with outside air. Moreover,the temperature rising of exhaust air in the heat exchanger (30) issuppressed by the humidifying part (42) of the heat exchanger (30). As aresult of such arrangement, it becomes possible to maintain a differencein temperature between the exhaust air and the compressed air, therebypromoting the transfer of heat from the compressed air to the exhaustair.

Accordingly, the present embodiment ensures that compressed aircompressed in the compressor (21) is positively cooled down to furtherlower temperatures. Because of this, it is possible to reduce thecompression ratio of the compressor (21) while at the same timemaintaining cooling capacity, and reduction in the input to thecompressor (21) is achieved. This makes it possible to provide animproved COP.

Furthermore, in the present embodiment, exhaust air that is expelledfrom the room for effecting ventilation is utilized for compressed aircooling. Exhaust air is not simply expelled to the outside of the room,that is, cold of the exhaust air is recovered to the compressed air.Because of this, room ventilation can be carried out without having toincrease room air-conditioning load to a greater extent, thereby makingit possible to reduce energy loss.

Further, by virtue of the humidifying part (42) of the heat exchanger(30), moisture evaporation latent heat is utilized to the full in such arange that no condensation occurs in the exhaust air, for compressed aircooling. Because of this, it is possible to achieve compressed aircooling by making utilization of a latent heat of vaporization ofmoisture without having to process drain water.

In addition, in the present embodiment, compressed air is cooled withexhaust air the flow rate of which is lower than that of the compressedair. However, as describe above, since it is possible to achieve coolingof the compressed air by making utilization of a latent heat ofvaporization of the moisture supplied to the exhaust air, this makes itpossible to cool the compressed air to a sufficiently low temperature,even in such a case.

Further, the humidifying cooler (41) and the humidifying part (42) ofthe heat exchanger (30) each are formed so as to gradually supplymoisture to exhaust air through the moisture permeable membrane. Thisarrangement therefore makes it possible to cause the moisture thussupplied to be evaporated positively in the exhaust air and, as aresult, the moisture supplied into the exhaust air will not remain inthe phase of liquid. Accordingly, the latent heat of vaporization of themoisture is utilized to the full for compressed air cooling withouttaking into consideration drain processing at all.

Additionally, it is possible to deliver, after performing separation ofmoisture from compressed air by the demoisturizer (22), the compressedair to the expansion device (23). This therefore makes it possible tocause the compressed air low in moisture content to expand, therebyproviding protection against the occurrence of condensation in thepost-expansion low-temperature air. As a result, it becomes possible tocool the room while preventing liquid droplets from being emitted,together with low-temperature air, into the room.

Further, in accordance with the demoisturizer (22), it is possible toseparate moisture from compressed air in the form of water vapor withoutcondensation. Because of this, it is possible to lower the enthalpy ofcompressed air that is delivered to the expansion device (23) to afurther extent. This therefore increases cooling capacity, therebyproviding a further improved COP.

In addition, the low-pressure space of the demoisturizer (22) isdepressurized by the vacuum pump (36), thereby making it possible toensure a different in partial pressure of water-vapor between thelow-pressure space and the high-pressure space at all times.Accordingly, water vapors in the compressed air penetrate through theseparation membrane at all times, so that separation of water vapor fromcompressed air can be carried out positively. As a result, it ispossible to provide an improved COP. Further, also during start-up, itis possible to ensure a difference in partial pressure of water-vaporbetween both the sides of the separation membrane, thereby making itpossible to shorten the time taken to provide sufficient coolingcapacity from the start-up.

Further, moisture separated from compressed air is supplied tolow-temperature air through the second water line (52). This providesprotection against excessive drop in room humidity, thereby making itpossible to maintain not only room temperature but also room humidity inspecified ranges to improve comfortability of the person present in theroom.

Additionally, moisture separated from compressed air is supplied,through the first water line (51), to the humidifying cooler (41) and tothe humidifying part (42). And then, the moisture can be supplied to theexhaust air in the humidifying cooler (41) and in the humidifying part(42) and it is possible to make use of moisture separated fromcompressed air for providing compressed air cooling in the heatexchanger (30). As a result, it becomes possible to reduce the amount ofwater required for running operations.

Further, it is arranged such that a mixture of low-temperature air androom air is supplied into the room. This provides protection againstexcessive drop in the temperature of air that is emitted into the room,thereby making it possible to maintain comfortability of the personpresent in the room.

FIRST VARIATION

In the above-described embodiment, low-temperature air from theexpansion device (23) and room air are mixed together and supplied intothe room. Instead of such arrangement, only low-temperature air may besupplied into the room. That is, there are cases in which thetemperature of low-temperature air dose not become so low depending uponthe running condition (for example, about 15 degrees centigrade). Insuch a case, even when only low-temperature air is supplied into theroom, there is no danger of causing discomfort to the person present inthe room. Accordingly, only low-temperature air may be sent out to theroom without being mixed with room air.

SECOND VARIATION

Further, in the above-described embodiment, moisture separated fromcompressed air in the demoisturizer (22) is supplied to exhaust airthrough the first water line (51) and to low-temperature air through thesecond water line (52). However, the moisture is not necessarilysupplied to both of the exhaust air and the low-temperature air. Themoisture may be supplied either to the exhaust air or to thelow-temperature air.

THIRD VARIATION

Further, in the above-described embodiment, moisture separated fromcompressed air in the demoisturizer (22) is supplied to the humidifyingcooler (41) and to the humidifying part (42). However, an arrangementmay be made in which one end of the first water line (51) is connectedto the inlet duct (43) and the separated moisture is supplied to exhaustair within the inlet duct (43). Further, another arrangement may be madein which one end of the first water line (51) is connected to the outletduct (44) and the separated moisture is supplied to exhaust air whichhas exchanged heat with compressed air in the heat exchanger (30).

FOURTH VARIATION

Further, in the above-described embodiment, the demoisturizer (22) isinterposed between the heat exchanger (30) and the expansion device (23)in the cycle-side system (20). However, an arrangement may be made inwhich the demoisturizer (22) is interposed between the compressor (21)and the heat exchanger (30) and moisture is separated from compressedair prior to cooling by the heat exchanger (30). Furthermore, like thethird variation, in the present variation moisture separated fromcompressed air may be supplied either to exhaust air within the inletduct (43) or to exhaust air within the outlet duct (44).

FIFTH VARIATION

Moreover, in the above-described embodiment, the low-pressure space ofthe demoisturizer (22) is subjected to depressurization by the vacuumpump (36) and moisture separated from compressed air by thedemoisturizer (22) is utilized for room humidification, exhaust aircooling, et cetera. However, an arrangement may be made in which thevacuum pump (36) is not provided and the configuration of thedemoisturizer (22) is changed so that water vapor in compressed airpasses through the separation membrane and moves to exhaust air.

That is, defined in the demoisturizer are a cycle-side space and anexhaust heat-side space which are separated from each other by aseparation membrane. Compressed air cooled in the heat exchanger (30) isdirected to the cycle-side space. On the other hand, the inlet duct (43)of the exhaust heat-side system (40) is connected to the exhaustheat-side space and the exhaust heat-side space is defined at a halfwayportion of the inlet duct (43). In such a case, only the water supplypipe (50) is connected to the humidifying cooler (41) and to thehumidifying part (42) so that only tap water et cetera from the outsideis supplied to the humidifying cooler (41) and to the humidifying part(42).

Owing to the difference in partial pressure of water-vapor createdbetween the cycle-side space and the exhaust heat-side space, watervapor in compressed air penetrates through the separation membrane andtravels to exhaust air. Thereafter, the water vapor thus separated isexpelled to the outside of the room, together with the exhaust air.Accordingly, the present variation makes drain processingunnecessitated.

INDUSTRIAL APPLICABILITY

As described above, the air-conditioning apparatus of the presentinvention is useful for room cooling and particularly applicable to aircycle cooling.

What is claimed is:
 1. An air-conditioning apparatus which cools roomair by an air cycle employing air as a refrigerant for performingair-cooling, comprising: means for directing room air to the apparatus;a compressor which draws in the room air for compressing said drawn roomair; cooling means which subjects said compressed air compressed in saidcompressor to heat exchange with exhaust air expelled from the room forcooling said compressed air; means for delivering exhaust air to saidcooling means; moisturizing means which supplies moisture to saidexhaust air that is delivered to said cooling means for pre-cooling saidexhaust air, wherein when said exhaust air is expelled from said coolingmeans said moisturizing means supplies a specified amount of moisture tosaid exhaust air so that said exhaust air has a relative humidity in arange from not less than 80% to less than 100%; and an expansion devicewhich provides expansion of said compressed air cooled by said coolingmeans wherein low-temperature air cooled by said expansion in saidexpansion device is delivered into the room.
 2. An air-conditioningapparatus which cools room air by an air cycle employing air as arefrigerant for performing air-cooling, comprising: means for directingroom air to the apparatus; a compressor which draws in the room air forcompressing said drawn room air; moisturizing means which supplymoisture to said exhaust air that is delivered to said cooling means forpre-cooling said exhaust air, wherein said moisturizing means suppliesmoisture to said exhaust air through a moisture permeable membranetransmittable to moisture; cooling means which subject said compressedair compressed in said compressor to heat exchange with exhaust airexpelled from the room for cooling said compressed air; means fordelivering exhaust air to said cooling means; and an expansion devicewhich provides expansion of said compressed air cooled by said coolingmeans, wherein low-temperature air cooled by said expansion in saidexpansion device is delivered into the room.
 3. An air-conditioningapparatus which cools room air by an air cycle employing air as arefrigerant for performing air-cooling, comprising: means for directingroom air to the apparatus; a compressor which draws in the room air forcompressing said drawn room air; cooling means which subject saidcompressed air compressed in said compressor to heat exchange withexhaust air expelled from the room for cooling said compressed air;means for delivering exhaust air to said cooling means; an expansiondevice which provides expansion of said compressed air cooled by saidcooling means, wherein low-temperature air cooled by expansion in saidexpansion device is delivered into the room; and demoisturizing meanswhich has a separation membrane, said separation membrane being formedsuch that water vapor in the air is allowed to pass therethrough from ahigh partial pressure of water-vapor side to a low partial pressure ofwater-vapor side thereof, for separation of water vapor contained insaid compressed air without causing said water vapor to undergocondensation.
 4. The air-conditioning apparatus of claim 3, furthercomprising depressurizing means which provides depressurization of oneof said sides of said separation membrane in said demoisturizing meansso as to ensure a difference in partial pressure of water-vapor betweenboth said separation membrane sides.
 5. The air-conditioning apparatusof claim 4, further comprising moisturizing means which suppliesmoisture to said exhaust air that is delivered to said cooling means forpre-cooling said exhaust air.
 6. The air-conditioning apparatus of claim5, wherein a part or all of moisture separated from said compressed airby said demoisturizing means is supplied to said exhaust air by saidmoisturizing means.
 7. The air-conditioning apparatus of claim 4,further comprising moisturizing means which supplies moisture to saidexhaust air so that cooling of said compressed air is performed makingutilization of a latent heat of vaporization of water in said coolingmeans.
 8. The air-conditioning apparatus of claim 7, wherein a part orall of moisture separated from said compressed air by saiddemoisturizing means is supplied to said exhaust air by saidmoisturizing means.
 9. The air-conditioning apparatus of claim 3,wherein said demoisturizing means is formed so that one of the surfacesof said separation membrane is brought into contact with said compressedair, and whereas the other of said surfaces is brought into contact withsaid exhaust air whereby water vapor contained in said compressed airwill travel to said exhaust air.
 10. The air-conditioning apparatus ofclaim 3, wherein a part or all of the moisture separated from saidcompressed air by said demoisturizing means is supplied together withlow-temperature air from said expansion device into said room.
 11. Theair-conditioning apparatus of claim 3, wherein said separation membraneis composed of a polymeric membrane and formed so as to allow watervapor to pass therethrough by water-molecule diffusion in said membrane.12. The air-conditioning apparatus of claim 3, wherein said separationmembrane has a large number of pores having a size equal to a moleculefree path and is formed so as to allow water vapor to pass therethroughby water-molecule capillary condensation and diffusion.
 13. Anair-conditioning apparatus which cools room air by an air cycleemploying air as a refrigerant for performing air-cooling, comprising:means for directing room air to the apparatus; a compressor which drawsin the room air for compressing said drawn room air, wherein saidcompressor is so formed as to draw in room air and supply air that issupplied from the outside to the inside of said room; cooling meanswhich subject said compressed air compressed in said compressor to heatexchange with exhaust air expelled from the room for cooling saidcompressed air; means for delivering exhaust air to said cooling means;and an expansion device which provides expansion of said compressed aircooled by said cooling means, wherein low-temperature air cooled by saidexpansion in said expansion device is delivered into the room.
 14. Anair-conditioning apparatus which cools room air by an air cycleemploying air as a refrigerant for performing air-cooling, comprising:means for directing room air to the apparatus; a compressor which drawsin the room air for compressing said drawn room air; cooling means whichsubject said compressed air compressed in said compressor to heatexchange with exhaust air expelled from the room for cooling saidcompressed air; means for delivering exhaust air to said cooling means;and an expansion device which provides expansion of said compressed aircooled by said cooling means, wherein low-temperature air from saidexpansion device is mixed with room air and thereafter said mixture issupplied into said room.
 15. An air-conditioning apparatus which coolsroom air by an air cycle employing air as a refrigerant for performingair-cooling, comprising: means for directing room air to the apparatus;a compressor which draws in the room air for compressing said drawn roomair; cooling means which subjects said compressed air compressed in saidcompressor to heat exchange with exhaust air expelled from the room forcooling said compressed air; means for delivering exhaust air to saidcooling means; moisturizing means which supply moisture to said exhaustair so that cooling of said compressed air is performed makingutilization of a latent heat of vaporization of water in said coolingmeans, wherein when said exhaust air is expelled from said cooling meanssaid moisturizing means supplies a specified amount of moisture to saidexhaust air so that said exhaust air has a relative humidity in a rangefrom not less than 80% to less than 100%; and an expansion device whichprovides expansion of said compressed air cooled by said cooling,wherein low-temperature air from said expansion device is mixed withroom air and thereafter said mixture is supplied into the room.
 16. Anair-conditioning apparatus which cools room air by an air cycleemploying air as a refrigerant for performing air-cooling, comprising:means for directing room air to the apparatus; a compressor which drawsin the room air for compressing said drawn room air; cooling means whichsubjects said compressed air compressed in said compressor to heatexchange with exhaust air expelled from the room for cooling saidcompressed air; means for delivering exhaust air to said cooling means;moisturizing means which supply moisture to said exhaust air through amoisture permeable membrane transmittable to moisture, so that coolingof said compressed air is performed making utilization of a latent heatof vaporization of water in said cooling means; and an expansion devicewhich provides expansion of said compressed air cooled by said coolingmeans, wherein low-temperature air cooled by said expansion in saidexpansion device is delivered into the room.